In a Dense Wavelength Division Multiplexed (DWDM) optical transmission system, optical performance may vary across the optical channels. The worst performing channels lead to a system performance bottle-neck. A main source of the channel performance unbalance is a channel power unbalance, or undesired tilt, of the optical channels in an optical fiber span that carries the optical channels from a transmit end to a receive end of the system. The channel power unbalance generates non-linear impairment unbalance in which channels having relatively higher power generate more impairment to neighboring channels and to themselves than do channels with relatively lower power. In addition, channel power unbalance causes unbalanced optical signal-to-noise ratios (OSNRs) at the receive end, where channels with lower power experience lower OSNRs than do channels input with higher power.